How do I set the Seed value to 0 under the Sampling tab?
I believe you are misunderstanding the meaning of the seed value.

Seed is not how much noise there will be in your render. Seed is basically the pattern the noise will have. Noise is a natural byproduct of the way Cycles (and any ray-tracing renderer) renders the scene. There are many methods for eliminating noise in Blender, but the primary method is to raise the samples.

There are so many resources on this topic, because it is really the major factor in whether a scene feasible to render. If we could render everything with one sample, we wouldn't really need to worry about render times, as long as our poly-count didn't exceed our memory.